/* Parse function for JavaScript. Makes use of the tokenizer from
 * tokenizejavascript.js. Note that your parsers do not have to be
 * this complicated -- if you don't want to recognize local variables,
 * in many languages it is enough to just look for braces, semicolons,
 * parentheses, etc, and know when you are inside a string or comment.
 *
 * See manual.html for more info about the parser interface.
 */

var JSParser = Editor.Parser = (function() {
  // Token types that can be considered to be atoms.
  var atomicTypes = {"atom": true, "number": true, "variable": true, "string": true, "regexp": true};
  // Setting that can be used to have JSON data indent properly.
  var json = false;
  // Constructor for the lexical context objects.
  function JSLexical(indented, column, type, align, prev, info) {
	// indentation at start of this line
	this.indented = indented;
	// column at which this scope was opened
	this.column = column;
	// type of scope ('vardef', 'stat' (statement), 'form' (special form), '[', '{', or '(')
	this.type = type;
	// '[', '{', or '(' blocks that have any text after their opening
	// character are said to be 'aligned' -- any lines below are
	// indented all the way to the opening character.
	if (align != null)
	  this.align = align;
	// Parent scope, if any.
	this.prev = prev;
	this.info = info;
  }

  // My favourite JavaScript indentation rules.
  function indentJS(lexical) {
	return function(firstChars) {
	  var firstChar = firstChars && firstChars.charAt(0), type = lexical.type;
	  var closing = firstChar == type;
	  if (type == "vardef")
		return lexical.indented + 4;
	  else if (type == "form" && firstChar == "{")
		return lexical.indented;
	  else if (type == "stat" || type == "form")
		return lexical.indented + indentUnit;
	  else if (lexical.info == "switch" && !closing)
		return lexical.indented + (/^(?:case|default)\b/.test(firstChars) ? indentUnit : 2 * indentUnit);
	  else if (lexical.align)
		return lexical.column - (closing ? 1 : 0);
	  else
		return lexical.indented + (closing ? 0 : indentUnit);
	};
  }

  // The parser-iterator-producing function itself.
  function parseJS(input, basecolumn) {
	// Wrap the input in a token stream
	var tokens = tokenizeJavaScript(input);
	// The parser state. cc is a stack of actions that have to be
	// performed to finish the current statement. For example we might
	// know that we still need to find a closing parenthesis and a
	// semicolon. Actions at the end of the stack go first. It is
	// initialized with an infinitely looping action that consumes
	// whole statements.
	var cc = [json ? expressions : statements];
	// Context contains information about the current local scope, the
	// variables defined in that, and the scopes above it.
	var context = null;
	// The lexical scope, used mostly for indentation.
	var lexical = new JSLexical((basecolumn || 0) - indentUnit, 0, "block", false);
	// Current column, and the indentation at the start of the current
	// line. Used to create lexical scope objects.
	var column = 0;
	var indented = 0;
	// Variables which are used by the mark, cont, and pass functions
	// below to communicate with the driver loop in the 'next'
	// function.
	var consume, marked;

	// The iterator object.
	var parser = {next: next, copy: copy};

	function next(){
	  // Start by performing any 'lexical' actions (adjusting the
	  // lexical variable), or the operations below will be working
	  // with the wrong lexical state.
	  while(cc[cc.length - 1].lex)
		cc.pop()();

	  // Fetch a token.
	  var token = tokens.next();

	  // Adjust column and indented.
	  if (token.type == "whitespace" && column == 0)
		indented = token.value.length;
	  column += token.value.length;
	  if (token.content == "\n"){
		indented = column = 0;
		// If the lexical scope's align property is still undefined at
		// the end of the line, it is an un-aligned scope.
		if (!("align" in lexical))
		  lexical.align = false;
		// Newline tokens get an indentation function associated with
		// them.
		token.indentation = indentJS(lexical);
	  }
	  // No more processing for meaningless tokens.
	  if (token.type == "whitespace" || token.type == "comment")
		return token;
	  // When a meaningful token is found and the lexical scope's
	  // align is undefined, it is an aligned scope.
	  if (!("align" in lexical))
		lexical.align = true;

	  // Execute actions until one 'consumes' the token and we can
	  // return it.
	  while(true) {
		consume = marked = false;
		// Take and execute the topmost action.
		cc.pop()(token.type, token.content);
		if (consume){
		  // Marked is used to change the style of the current token.
		  if (marked)
			token.style = marked;
		  // Here we differentiate between local and global variables.
		  else if (token.type == "variable" && inScope(token.content))
			token.style = "js-localvariable";
		  return token;
		}
	  }
	}

	// This makes a copy of the parser state. It stores all the
	// stateful variables in a closure, and returns a function that
	// will restore them when called with a new input stream. Note
	// that the cc array has to be copied, because it is contantly
	// being modified. Lexical objects are not mutated, and context
	// objects are not mutated in a harmful way, so they can be shared
	// between runs of the parser.
	function copy(){
	  var _context = context, _lexical = lexical, _cc = cc.concat([]), _tokenState = tokens.state;

	  return function copyParser(input){
		context = _context;
		lexical = _lexical;
		cc = _cc.concat([]); // copies the array
		column = indented = 0;
		tokens = tokenizeJavaScript(input, _tokenState);
		return parser;
	  };
	}

	// Helper function for pushing a number of actions onto the cc
	// stack in reverse order.
	function push(fs){
	  for (var i = fs.length - 1; i >= 0; i--)
		cc.push(fs[i]);
	}
	// cont and pass are used by the action functions to add other
	// actions to the stack. cont will cause the current token to be
	// consumed, pass will leave it for the next action.
	function cont(){
	  push(arguments);
	  consume = true;
	}
	function pass(){
	  push(arguments);
	  consume = false;
	}
	// Used to change the style of the current token.
	function mark(style){
	  marked = style;
	}

	// Push a new scope. Will automatically link the current scope.
	function pushcontext(){
	  context = {prev: context, vars: {"this": true, "arguments": true}};
	}
	// Pop off the current scope.
	function popcontext(){
	  context = context.prev;
	}
	// Register a variable in the current scope.
	function register(varname){
	  if (context){
		mark("js-variabledef");
		context.vars[varname] = true;
	  }
	}
	// Check whether a variable is defined in the current scope.
	function inScope(varname){
	  var cursor = context;
	  while (cursor) {
		if (cursor.vars[varname])
		  return true;
		cursor = cursor.prev;
	  }
	  return false;
	}

	// Push a new lexical context of the given type.
	function pushlex(type, info) {
	  var result = function(){
		lexical = new JSLexical(indented, column, type, null, lexical, info)
	  };
	  result.lex = true;
	  return result;
	}
	// Pop off the current lexical context.
	function poplex(){
	  if (lexical.type == ")")
		indented = lexical.indented;
	  lexical = lexical.prev;
	}
	poplex.lex = true;
	// The 'lex' flag on these actions is used by the 'next' function
	// to know they can (and have to) be ran before moving on to the
	// next token.

	// Creates an action that discards tokens until it finds one of
	// the given type.
	function expect(wanted){
	  return function expecting(type){
		if (type == wanted) cont();
		else if (wanted == ";") pass();
		else cont(arguments.callee);
	  };
	}

	// Looks for a statement, and then calls itself.
	function statements(type){
	  return pass(statement, statements);
	}
	function expressions(type){
	  return pass(expression, expressions);
	}
	// Dispatches various types of statements based on the type of the
	// current token.
	function statement(type){
	  if (type == "var") cont(pushlex("vardef"), vardef1, expect(";"), poplex);
	  else if (type == "keyword a") cont(pushlex("form"), expression, statement, poplex);
	  else if (type == "keyword b") cont(pushlex("form"), statement, poplex);
	  else if (type == "{") cont(pushlex("}"), block, poplex);
	  else if (type == ";") cont();
	  else if (type == "function") cont(functiondef);
	  else if (type == "for") cont(pushlex("form"), expect("("), pushlex(")"), forspec1, expect(")"), poplex, statement, poplex);
	  else if (type == "variable") cont(pushlex("stat"), maybelabel);
	  else if (type == "switch") cont(pushlex("form"), expression, pushlex("}", "switch"), expect("{"), block, poplex, poplex);
	  else if (type == "case") cont(expression, expect(":"));
	  else if (type == "default") cont(expect(":"));
	  else if (type == "catch") cont(pushlex("form"), pushcontext, expect("("), funarg, expect(")"), statement, poplex, popcontext);
	  else pass(pushlex("stat"), expression, expect(";"), poplex);
	}
	// Dispatch expression types.
	function expression(type){
	  if (atomicTypes.hasOwnProperty(type)) cont(maybeoperator);
	  else if (type == "function") cont(functiondef);
	  else if (type == "keyword c") cont(expression);
	  else if (type == "(") cont(pushlex(")"), expression, expect(")"), poplex, maybeoperator);
	  else if (type == "operator") cont(expression);
	  else if (type == "[") cont(pushlex("]"), commasep(expression, "]"), poplex, maybeoperator);
	  else if (type == "{") cont(pushlex("}"), commasep(objprop, "}"), poplex, maybeoperator);
	  else cont();
	}
	// Called for places where operators, function calls, or
	// subscripts are valid. Will skip on to the next action if none
	// is found.
	function maybeoperator(type, value){
	  if (type == "operator" && /\+\+|--/.test(value)) cont(maybeoperator);
	  else if (type == "operator") cont(expression);
	  else if (type == ";") pass();
	  else if (type == "(") cont(pushlex(")"), commasep(expression, ")"), poplex, maybeoperator);
	  else if (type == ".") cont(property, maybeoperator);
	  else if (type == "[") cont(pushlex("]"), expression, expect("]"), poplex, maybeoperator);
	}
	// When a statement starts with a variable name, it might be a
	// label. If no colon follows, it's a regular statement.
	function maybelabel(type){
	  if (type == ":") cont(poplex, statement);
	  else pass(maybeoperator, expect(";"), poplex);
	}
	// Property names need to have their style adjusted -- the
	// tokenizer thinks they are variables.
	function property(type){
	  if (type == "variable") {mark("js-property"); cont();}
	}
	// This parses a property and its value in an object literal.
	function objprop(type){
	  if (type == "variable") mark("js-property");
	  if (atomicTypes.hasOwnProperty(type)) cont(expect(":"), expression);
	}
	// Parses a comma-separated list of the things that are recognized
	// by the 'what' argument.
	function commasep(what, end){
	  function proceed(type) {
		if (type == ",") cont(what, proceed);
		else if (type == end) cont();
		else cont(expect(end));
	  }
	  return function commaSeparated(type) {
		if (type == end) cont();
		else pass(what, proceed);
	  };
	}
	// Look for statements until a closing brace is found.
	function block(type){
	  if (type == "}") cont();
	  else pass(statement, block);
	}
	// Variable definitions are split into two actions -- 1 looks for
	// a name or the end of the definition, 2 looks for an '=' sign or
	// a comma.
	function vardef1(type, value){
	  if (type == "variable"){register(value); cont(vardef2);}
	  else cont();
	}
	function vardef2(type, value){
	  if (value == "=") cont(expression, vardef2);
	  else if (type == ",") cont(vardef1);
	}
	// For loops.
	function forspec1(type){
	  if (type == "var") cont(vardef1, forspec2);
	  else if (type == ";") pass(forspec2);
	  else if (type == "variable") cont(formaybein);
	  else pass(forspec2);
	}
	function formaybein(type, value){
	  if (value == "in") cont(expression);
	  else cont(maybeoperator, forspec2);
	}
	function forspec2(type, value){
	  if (type == ";") cont(forspec3);
	  else if (value == "in") cont(expression);
	  else cont(expression, expect(";"), forspec3);
	}
	function forspec3(type) {
	  if (type == ")") pass();
	  else cont(expression);
	}
	// A function definition creates a new context, and the variables
	// in its argument list have to be added to this context.
	function functiondef(type, value){
	  if (type == "variable"){register(value); cont(functiondef);}
	  else if (type == "(") cont(pushlex(")"), pushcontext, commasep(funarg, ")"), poplex, statement, popcontext);
	}
	function funarg(type, value){
	  if (type == "variable"){register(value); cont();}
	}

	return parser;
  }

  return {
	make: parseJS,
	electricChars: "{}:",
	configure: function(obj) {
	  if (obj.json != null) json = obj.json;
	}
  };
})();
